The Registry for Research on Hormonal Transplacental Carcinogenesis plans to continue its investigations of the epidemiology, pathogenesis, biologic characteristics, management and prognosis of human genital cancers that develop after intrauterine exposure to exogenous sex hormones. A data bank, which has been developed with details of each case, will be continued and expanded for conduct of this research. Active canvassing of medical institutions and tumor registries will continue in order to obtain all cases of clear cell adenocarcinoma of the genital tract occurring in females born after 1940, with or without a history of hormone exposure, as well as all cases of other types of genital cancer that develop in individuals exposed to either diethylstibestrol (DES) or any other type of sex hormones including those of steroidal nature. Studies on the age-incidence of DES-related clear cell adenocarcinoma will be extended, with particular emphasis on cases beyond age 24. A particular interest exists in squamous cell carcinomas of the vagina and cervix, which others have predicted will occur in large numbers in the exposed population. Detailed clinicopathologic correlative studies will be directed toward a wide variety of host and cancer characteristics that may be related to the nature and behavior of the tumor. The investigation of lesions that precede clear cell adenocarcinoma will continue and the existing incomplete knowledge of treatment and prognosis will be expanded. We shall remain a source of scientific information and consultation for this problem, and provide mechanisms by which qualified investigators may gain access to biologic materials from patients with these cancers.